Net Income Per Common Share - Basic and Diluted Net Income Per Common Share Calculations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2018
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income from continuing operations	$ 53.1	$ 56.0	$ (136.8)	$ 27.9	$ 48.1	$ 36.5	$ 29.9	$ 13.0	$ 0.2	$ 127.5	$ 95.9
Income (loss) from discontinued operations, net of taxes	0.0	0.0	0.0	0.1	(0.1)	0.2	(0.2)	(0.1)	0.1	(0.1)	1.8
Net income	$ 53.1	$ 56.0	$ (136.8)	$ 28.0	$ 47.9	$ 36.8	$ 29.7	$ 13.0	$ 0.3	$ 127.4	$ 97.8
Weighted-average common and common equivalent shares outstanding—Basic (in shares)									66.9	66.6	66.1
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Weighted-average common and common equivalent shares outstanding—Diluted (in shares)									67.3	66.9	66.4
Net income per common share — Basic
Income from continuing operations (usd per share)	$ 0.79	$ 0.84	$ (2.05)	$ 0.42	$ 0.72	$ 0.55	$ 0.45	$ 0.20	$ 0.00	$ 1.92	$ 1.45
Income from discontinued operations (usd per share)	0	0	0	0	0	0	0	0	0	0	0.03
Net income (usd per share)	0.79	0.84	(2.05)	0.42	0.72	0.55	0.45	0.20	0.00	1.91	1.48
Net income per common share — Diluted
Income from continuing operations (usd per share)	0.78	0.83	(2.05)	0.41	0.71	0.55	0.45	0.20	0.00	1.91	1.45
Income from discontinued operations (usd per share)	0	0	0	0	0	0	0	0	0	0	0.03
Net income (usd per share)	$ 0.78	$ 0.83	$ (2.05)	$ 0.42	$ 0.71	$ 0.55	$ 0.45	$ 0.19	$ 0.00	$ 1.90	$ 1.47
RSUs
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilutive securities (in shares)									0.1	0.2	0.1
Stock options
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilutive securities (in shares)									0.1	0.1	0.1
Performance shares
Incremental Weighted Average Shares Attributable to Dilutive Effect [Abstract]
Effect of dilutive securities (in shares)									0.1	0.1	0.0